1. Field of Endeavor
The present invention relates to devices, systems, and processes useful as needles and injectors, and more specifically to retrobulbar needles.
2. Brief Description of the Related Art
Many opthalmology procedures are performed with a local anesthetic and intravenous sedation. Retrobulbar or peribulbar (behind the eye or adjacent to the eye) injections of local anesthetic are often used for intraocular surgeries, such as cataract extraction, retinal, vitreous, corneal, and pterygium surgeries. Retrobulbar injections are typically performed by placing a 1½ or 1¼ inch needle through the lateral lower lid adjacent to the inferior orbital rim and pushing deep into the orbit. In some cases the needle may be directed superomedially when it is deep in the orbit. This movement is to permit better flow of local anesthetic into the orbital apex. The local anesthetic is injected after the needle is in place. The needle is then withdrawn. The purpose of the local anesthetic is to provide anesthesia and akinesia (prevent movements of the eye which is critical during delicate intraocular surgery).
Peribulbar injections of local anesthetic involve placing the needle through the lateral lower lid adjacent to inferior orbital rim. However, the needle is not pushed as deep into the orbit as with a retrobulbar injection.
During these procedures, the surgeon cannot visualize the needle or orbital structures with this technique; that is, the needle is placed blindly. Therefore, vital structures such as the optic nerve, blood vessels, extraocular muscles, and the eye cannot be avoided.
Many complications can occur during retrobulbar, and to a lesser extent peribulbar, injections of local anesthetic. A retrobulbar hemorrhage can occur if the needle encounters a blood vessel. A severe retrobulbar hemorrhage can place pressure on the optic nerve and cause blindness. The needle can also puncture the eye which may result in severe visual loss. The needle can also penetrate the optic nerve sheath. The injection of a commonly used anesthetic, bupivicaine, causes respiratory arrest in these cases. An injection into an extraocular muscle can cause double vision.
An effort to avoid these complications has been the use of anesthetic eyedrops alone for cataract extractions. This technique is not possible in patients who are not cooperative and are too anxious. The use of anesthetic eyedrops alone is not possible for long surgeries such as retinal or vitreous surgeries. Retrobulbar anesthesia is still needed for patients who are anxious, unable to cooperate, or for retinal or vitreous surgeries, or corneal transplants.
An effort to reduce the complications of retrobulbar anesthetic injections is shown with the metal Atkinson retrobulbar needle. This needle is somewhat more rounded at the tip than typical needles used for local anesthetic injections. However, the needle is still sharp and metallic and can cause all of the complications listed above.
Another problem is that the injection is out the distal end of the needle only. The surgeon must angle the needle toward the optic nerve to make the anesthetic flow toward the orbital apex. This maneuver increases the rate of complications described above.
Greenbaum (U.S. Pat. No. 5,407,441, “Opthalmologic cannula”) describes an opthalmologic cannula that has a blunt end. The blunt flexible cannula made of plastic is introduced into the orbit for a retrobulbar injection. The plastic is semi-flexible, but not soft. The cannula therefore still has the potential to tear a blood vessel or nerve. Furthermore, the surgeon must make an incision in the skin, muscle, and septum of the eyelid with scissors in order to allow the cannula to enter the orbit. The cannula has not been used because of the necessity of making an incision.
Longren et al (U.S. Pat. No. 4,886,506, “Soft tip catheter”) describes a more rigid catheter with a softer section over the very distal portion of the catheter. It is used for coronary angiography to provide better torque control, but has a soft tip to avoid injury to the tissues. It is not a needle. Additional procedures and devices are needed to get the cannula into the blood vessel.
Razi (U.S. Pat. No. 5,542,936, “Sheath for introducing catheter”) describes an introducer sheath for introducing a catheter into a blood vessel. There are fenestrations in the bend of the sheath for the flow of blood. This device has four separate pieces.
Gupta (U.S. Pat. No. 5,718,693, “Hematoma prevention apparatus and method”) describes a needle which is placed in a blood vessel, a guidewire is placed through the needle into the vessel, and the needle is withdrawn. A cannula is then introduced over the guidewire. A sheath is then placed over the cannula such that part of the sheath is in the blood vessel and part is outside the skin. This prevents blood from leaking out of the blood vessel and causing a hematoma. This device uses four separate pieces.
Del Cerro et al (U.S. Pat. No. 5,273,530, “Intraretinal delivery and withdrawal instruments” and U.S. Pat. No. 5,409,457, “Intraretinal delivery and withdrawal instruments”) describe a curved needle which has a very short sharp segment on the end. It is placed beneath the conjunctiva close to the eye and then pushed through the sclera posteriorly into the eye in the subretinal space. The sharp tip of the needle is always exposed. The needle does not go through the eyelid. The sharp needle tip is not covered at any time.
Erskine (U.S. Pat. No. 5,795,339 “Catheter-advancement actuated needle retraction system”) describes a needle for intravenous use whereby the needle retracts inside an outer sheath after the needle has entered the vein. A spring mechanism is used. The mechanism allows the needle to be thrown away after its use with the sharp end retracted to avoid an inadvertent of a needle stick injury to the physician or nurse. The retactor mechanism is not used to protect structures in the patient.
Sorenson et al (U.S. Patent Application Publication No. 2002/0123723 A1, “Apparatus and method for specific interstitial or subcutaneous diffusion and dispersion of medication”) describes a tube in which a sharp-pointed stylette is placed. The stylette allows the tube with the stylette to be pushed through a lining into the body for treatment. The stylette is removed and the tube can be pushed safely further into the body. Medication can then be injected through the tube into the body. Holes in the sidewall of the tube permit dispersion of the medication. The durometer of the material can be variable. This device involves two separate pieces.
Vaillancourt (U.S. Pat. No. 4,655,750, “Closed system catheter with guide wire”) describes a needle with a sheath over it. The needle and sheath are introduced into a vein. The needle is withdrawn and a guidewire is pushed through the sheath into the vein. The sheath is pushed in further and the guidewire is withdrawn. This system has three separate pieces and does not protect the tissues when the needle is in place.
Couston et al (U.S. Patent Application Publication No. 2006/0149194, “Ophthalmic microsurgical system”) describes an outer blunt cannula that can be flexible. The cannula is placed in the eye through a surgical incision. The end of the cannula is placed close to Schlemm's canal inside the eye. Various instruments can be passed through the cannula (e.g., knife, needle, etc.) to perform procedures on Schlemm's canal without injuring other intraocular structures. The instrument is never placed in the orbit. The procedure is performed under direct visualization.
Rogers (U.S. Pat. No. 5,531,692, “Safety syringe”) with a plunger mechanism. There is an outer sheath over the needle. When the plunger is pushed, the needle tip sticks out the sheath. The needle tip retracts inside the sheath when there is no pressure on the plunger. The needle is used to prevent accidental needle-sticks in medical personnel.
Needles are also used during other types of surgery for the injection of local anesthetic. In many procedures, the same syringe and needle are used repeatedly. That is because the local anesthetic effect may dissipate during the procedure, or the surgery may extend to more areas that were not anesthetized by the original injections. In other cases, areas of bleeding require additional injections to allow the epinephrine in the local anesthetic to constrict the blood vessels and stop the bleeding.
The same needle and syringe are used repeatedly because of the added time (and cost) to obtain a new needle for each of many injections. The cap must be placed on the needle between uses. The needle and syringe must be picked up, placed on a tray, handed from the surgical technician to the surgeon and vice versa, and otherwise handled. All of these maneuvers place the operating personnel at a risk for an accidental needle stick and the transmission of disease such as HIV and hepatitis C.
There are various safety needles for injections and the placement of intravenous lines available. However, all of these needles and intravenous needles/lines are for a single use only.